A new model for the infrared brightness of the galaxy

Abstract

We present a model that reproduces the near-infrared brightness distribution of the Galaxy, and we compare its predictions with the results of the Spacelab observations obtained by Kent et al. and the COBE DIRBE experiment. We examine characteristics of nearby spiral galaxies as a guide for a consistent description of the bulge, the bar and spiral arms. A Monte Carlo method is used to generate a 3D model of each component of the Galaxy; the density flux contribution of the pseudo-stars created in this way is then added in a longitude versus latitude grid to produce contour maps and brightness profiles. We estimate the mass of the components, based on a calibration of the flux density per unit mass for the characteristic stellar population of each component. We find that the brightness of the disc is better reproduced by the Freeman radial density profile, which presents a central hole, than by a classical disc with exponential profile extending to the centre. We show that the rotation curve obtained from the mass distribution of the model is consistent with the observed one.